It is known from the state of the art to dehumidify moist wood and similar biomasses such as grass or corn or even hygroscopic synthetic materials by means of drying devices such as drum dryers, belt dryers, entrained-flow dryers or chute dryers which are usually operated with primary energy inputs such as oil, gas, coal or even process heat. The material to be dried will not be subjected to any relevant mechanical stresses in these drying devices, which leads to the consequence that the material and cell structures will be in a relative idle state during the drying process, or will only move at a comparatively low speed. Due to the lack of mechanical stresses of the material to be dehumidified during the drying process, the fluids enclosed in the material such as especially the contained capillary water and the water that is chemically bound by way of OH groups in the cell material will be expelled from the material to be tried only as a consequence of the supplied thermal energy in such a way that the fluids within the material will convert into the gaseous state and will exit from the material as a result of the occurring vapor pressure.
This usually leads to the consequence that the water expelled from the cell structures by the vapor pressure will return to the cell structure when the water vapor emitted from the material to be dried is not immediately removed from the ambient environment of the material, e.g. a wood particle.
That is why the aforementioned drying apparatuses of the state of the art are relatively energy-consuming.
It is a further common aspect in the aforementioned drying apparatuses that they require input material which needs to have a grain size which is predetermined within narrow limits and which must not vary strongly. They further require a relatively strong gas stream in order to remove the expelled water or water vapor and to thereby prevent a reuptake of the expelled water by the material.
Finally, the drying devices as described above come with the disadvantage that the dwell time of material in the devices is comparatively long, which consequently leads to high energy consumption that is caused by the method.
It is further known from the state of the art to process components which are composed of different materials such as metal parts, glass, rubber, wood, polymers, fibre materials and composite materials by means of powder-coated or plastic-coated aluminium profiles in impact reactors in which the components are crushed by impact stresses by means of impact elements.
In this connection, a method and an apparatus are known from EP 0 859 693 B1 for the processing of components made of mixed materials, especially mixed synthetic materials, in which an impact reactor comprises in its cylindrical base body a rotor that is rotatable by a drive motor. The rotor which is adjustable in its height consists of wear-proof steel and comprises detachably accommodated impact elements at its ends, which impact elements will crush the introduced components into fragments of different size produced by the impact stresses occurring during the impact, which fragments can subsequently be separated from one another. The entire specification does not provide any indication of crushing and simultaneously drying moist wood or other biological material.
It is further known from EP 1 057 531 A1 to inject water into an impact reactor during the crushing of wood and to remove by suction the occurring water vapor on the upper side of the reactor. The specification does not provide any indication of introducing moist wood into the reactor and of drying said wood under simultaneous supply of hot gases with a temperature of less than 95° C., especially less than 80° C., or the exhaust gas from a combustion process into the impact chamber which penetrates the material instead of the expelled water during impact stresses of the material.
It is therefore an object of the present invention to provide a method and an apparatus with which wood can be crushed and dried simultaneously with low energy input.